206-00-3 Brake System - General Information 206-00-3
DIAGNOSIS AND TESTING
Brake System
The brakes system operates by transferring effort
applied to the brake pedal by the driver to the
brakes at each wheel.
The braking effort is distributed to each wheel,
using a hydraulic system. The system is assisted
using a vacuum brake booster that reduces pedal
effort and increases hydraulic pressure.
The parking brake operates on the rear wheels
and is applied using a hand operated control.
lnspection and Verification
N0TE:Before carrying out any diagnosis, make
sure that the brake system warning indicator is
functional.
1. Verify the customer concern.
2. Visually inspect for obvious signs of mechanical
damage.
3. If an obvious cause for an observed or reported
concern is found, correct the case (if possible)
before proceeding to the next step.
4. If the cause if not visually evident, verify the
symptom and refer to the Symptom Chart.
Visual lnspection Chart
Road Test
1.
Perform a road test to compare actual vehicle
braking performance with the performance
standards expected by the driver. The ability of the
test driver to make valid comparisons and detect
performance deficiencies will depend on
experience.
Mechanical
- Tire pressure
- Wheels and tires
- Fluid leak from brake line(s)
The driver should have a thorough knowledge of
the brake system operation and accepted general
performance guidelines to make good comparisons
, and detect performance concerns.
An experienced technician will always establish a
route that will be used for all brake diagnosis road
tests. The road selected will be reasonably smooth and level. Gravel
or bumpy roads are not suitable
because the surface does not allow the tires to grip
the road equally. Crowned roads should be avoided
because of the large amount of weight shifted to
the low set of wheels on this type of road. Once
the route is established and consistently used, the
road surface variable can be eliminated from the
test results.
Before a road test, get a complete description of
the customer concerns or suspected condition.
From the description, the technician will be able to
match possible causes with symptoms. Certain
components will be identified as possible sources
while others will be eliminated by the evidence.
More importantly, the customer description can
reveal unsafe conditions which should be checked
or corrected before a road test. The description will
also help form the basic approach to the road test
by narrowing the concern to specific components,
vehicle speed or conditions.
Begin the road test with a general brake
performance check. Using the description of the
concern, test the brakes at different vehicle speeds
using both light and heavy pedal pressure.
Determine if the concern is in the front or rear
braking system. First use the foot brake and then
the parking brake. If the condition
(i.e. pull,
vibration, pulsation) occurs only on operation of
the parking brake, the concern is in the rear brake
system.
If the condition occurs when the foot brake
is depressed, the concern is in the front brake
system.
Avoid locking the brakes and sliding the tires. This
condition will not indicate brake efficiency. A heavily
braked but turning wheel will stop the vehicle in a
shorter distance than locked wheels.
If the concern becomes evident during this check,
make sure it fits the description given before the
road test. If the concern is not evident, attempt to
duplicate the condition using the information from
the description.
If a concern exists, use the Brake System Symptom
Chart in order to isolate it to a specific sub-system
and condition description. From this description, a
list of possible sources can be used to further
narrow the cause to a specific component or
condition.
- -
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206-00-5 Brake System - General Information 206-00-5
DIAGNOSIS AND TESTING
Symptom Possible Sources
Action
Grease or fluid on the brake
shoes or brake pads; glazed
linings. INSTALL
new brake shoes or
brake pads. REFER to:
Brake Shoes (206-02 Drum Brake, Removal and Installa-
tion),
Brake Pads (206-03 Front Disc
Brake, Removal and Installa-
tion),
Brake Pads (206-04 Rear Disc Brake, Removal and Installa-
tion).
I Stuck or seized calipers. I GO to Pinpoint Test A. I
Brake warning indicator always
on Low
brake fluid level. FILL the reservoir. CHECK the
brake and clutch system for
leaks including brake fluid in
the brake booster.
--
Leaking brake master cylinder
primary piston cup. INSTALL a new brake master
cylinder. REFER to: (206-06
Hydraulic Brake Actuation)
Brake Master Cylinder
- RHD
(Removal and Installation),
Brake Master Cylinder
- LHD
(Removal and Installation).
Parking brake control not fully
released. FREE UP and
ADJUST the
parking brake cable. REFER
to: (206-05 Parking Brake and
Actuation)
Parking Brake (Diagnosis and Testing),
Parking Brake Cable Adjust-
ment
- Vehicles With: Rear
Drum Brakes (General
Procedures),
Parking Brake Cable Adjust-
ment
- Vehicles With: Rear
Disc Brakes (General
Procedures).
INSTALL new components as
necessary.
I Shorted indicator circuit. I GO to Pinpoint Test B. I
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206-00-6 Brake System - General Information 206-00-6
DIAGNOSIS AND TESTING
Symptom
Vibration when the brakes are
applied Possible
Sources Action
Grease or fluid on the brake
shoes or brake pads; glazed
linings. INSTALL
new brake shoes or
brake pads. REFER to:
i
Brake Shoes (206-02 Drum
Brake, Removal and Installa-
tion),
Brake Pads (206-03 Front Disc
Brake, Removal and Installa-
tion),
Brake Pads (206-04 Rear Disc Brake, Removal and Installa-
tion).
Worn or damaged brake shoes
or brake pads. INSTALL
new brake shoes or
brake pads. REFER to:
Brake Shoes (206-02 Drum
Brake, Removal and Installa-
tion),
Brake Pads (206-03 Front Disc
Brake, Removal and Installa-
tion),
Brake Pads (206-04 Rear Disc
Brake, Removal and Installa-
tion).
Loose caliper mounting
bolt(s). TIGHTEN the caliper mounting
bolt(s). REFER to:
Specifications (206-03 Front Disc Brake, Specifications),
Specifications (206-04 Rear Disc Brake, Specifications).
Insufficient grease on sliding grease
where neces-
parts.
Damaged brake drum contact
surface. REFER to: Brake Drum (206-
02 Drum Brake, Removal and
Installation).
Loose or missing rear wheel
spindle bolts. TIGHTEN or
INSTALL new rear
wheel spindle bolts.
REFER to: Specifications (204-
02 Rear Suspension, Specifications).
Go to Pinpoint Test
C.
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206-00-1 0 Brake System - General Information 206-00-1 0
DIAGNOSIS AND TESTING
Pinpoint Tests
PINPOINT TEST A : BRAKES PULL OR DRIFT
TEST CONDITIONS
DETAILSIRESU LTSIACTIONS
A1 : ROAD TEST THE VEHICLE
Road test the vehicle and apply the brake pedal.
Does the vehicle pull or drift?
+ Yes
GO to A2.
+ No
Vehicle OK.
A2: TIRE INSPECTION
Check for excessive wear or incorrect tire pres-
sures.
Are the tires in good condition?
-, Yes
GO to A3.
+ No
INFLATE the tires to the correct pressure.
INSTALL new tires if excessively worn. TEST
the system for normal operation.
A3: BRAKE SHOE OR BRAKE PADS AND LINING INSPECTION
Inspect the brake shoes or brake pads for
grease or fluid on the linings and or wear
concerns.
Are any concerns present?
+ Yes
INSTALL new brake shoes or brake pads.
REFER to:
Brake Shoes (206-02 Drum Brake, Removal and
Installation),
Brake Pads (206-03 Front Disc Brake, Removal
and Installation),
Brake Pads (206-04 Rear Disc Brake, Removal
and Installation).
TEST the system for normal operation.
+ No
GO to A4.
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206=00-I 2 Brake System - General Information 206-00-1 2
DIAGNOSIS AND TESTING
TEST CONDITIONS
I A5: CHECK PRESSURE CONTROL VALVE-LEI T-HAND REAR I
Install pressure gauges in the right-hand front
and left-hand rear bleed nipples. Apply the brake
to read 6895
kPa (1000 psi) at the right-hand
front wheel.
- Read the pressure at left-hand rear wheel.
Does the pressure gauge read between 4692-
5164
kPa (680-750 psi) at the left-hand rear
wheel?
+ Yes
INSPECT the brake calipers and INSTALL
new components as required. REFER to:
Brake Shoes (206-02 Drum Brake, Removal and Installation),
Brake Pads (206-03 Front Disc Brake, Removal
and Installation),
Brake Pads (206-04 Rear Disc Brake, Removal
and Installation).
TEST the system for normal operation.
+ No
INSTALL a new left-hand rear brake pressure
control valve. BLEED the brake system.
REFER to: (206-00 Brake System
- General
Information)
Brake System Bleeding (General Procedures),
Brake System Pressure Bleeding (General Procedures).
TEST the system for normal operation.
PINPOINT TEST B
: BRAKE WARNING INDICATOR ALWAYS ON
TEST CONDITIONS
DETAILS/RESULTS/ACTIONS
I B1: CHECK BRAKE WARNING INDICATOR I
N0TE:The brake warning indicator should only illuminate when the ignition switch is in the START or
RUN position and the parking brake is applied.
I Ignition switch in position II.
Release the parking brake.
- Check the fluid level in the reservoir is at the
MAX mark.
Does the brake warning indicator illuminate?
+ Yes
REFER to: lnstrument Cluster
- Vehicles Built
Up To: 1 012005 (41 3-01 lnstrument Cluster,
Diagnosis and Testing).
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206-00-1 3 Brake System - General Information 206-00-1 3
DIAGNOSIS AND TESTING
TEST CONDITIONS DETAILSIRESU LTSIACTIONS
I B2: CHECK BRAKE SYSTEM FOR LEAKAGE 1
rn Check the brake master cylinder reservoir
sealing points and external brake and clutch
system for leaks. Refer to the brake master
cylinder component tests in this section.
Does the system leak?
-+ Yes
REPAIR as necessary. ADD fluid and BLEED
the brake system. REFER to: (206-00 Brake
System
- General Information)
Brake System Bleeding (General Procedures),
Brake System Pressure Bleeding (General Procedures).
TEST the system for normal operation.
183: CHECK BRAKE WARNING SWITCH OR WIRING I
I rn Ignition switch in position II. I
Remove the brake master cylinder reservoir
filler cap or switch. Allow the float to rest at its
lowest point.
Does the brake warning indicator illuminate?
-+ Yes
The switch or wiring is OK. TEST the system
for normal operation.
-+ No
REFER to: lnstrument Cluster - Vehicles Built I Up To: 1012005 (41 3-01 Instrument Cluster,
I Diagnosis and Testing).
PINPOINT TEST C : VIBRATION WHEN BRAKES ARE APPLIED
TEST CONDITIONS
DETAl LSIRESU LTSIACTIONS
Cl : ROAD TEST THE VEHICLE
Road test the vehicle without applying the
brakes at 40-80 kmlh (25-50 mph).
Is a vibration present?
-+ Yes
REFER to: Noise, Vibration and Harshness
(NVH) (1 00-04 Noise, Vibration and Harsh-
ness, Diagnosis and Testing).
After servicing, TEST the system for normal operation.
-+ No
GO to C2.
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206-00-1 5 Brake System - General Information 206-00-1 5
DIAGNOSIS AND TESTING
PINPOINT TEST D : PEDAL GOES DOWN FAST
Dl : ROAD TEST THE VEHICLE
rn Road test the vehicle and apply the foot brake.
Was the brake pedal effort normal?
+ Yes
Vehicle OK.
+ No
GO to
D2.
D2: CHECK BRAKE FLUID LEVEL
Check the brake master cylinder reservoir fluid
level.
Is the fluid level acceptable?
+ Yes
GO to D3.
+ NO
CHECK the brake master cylinder reservoir
sealing points for leaks. REFER to the brake
master cylinder component tests in this
section. ADD fluid and BLEED the brake
system. REFER to: (206-00 Brake System
-
General Information)
Brake System Bleeding (General Procedures),
Brake System Pressure Bleeding (General
Procedures).
TEST the system for normal operation.
/
2006.0 Fiesta 12/2006 G28494en
TEST CONDITIONS
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206-00-1 6 Brake System - General Information 206mOO-16
DIAGNOSIS AND TESTING
TEST CONDITIONS
2006.0 Fiesta 12/2006 G28494en
D3: PRESSURIZE THE SYSTEM
D4: CHECK FOR BRAKE SYSTEM LEAKS
Pump the foot brake rapidly five times.
Does the brake pedal height build up and then
hold?
+ Yes
CHECK parking brake adjustment and
ADJUST as necessary. REFER to: (206-05
Parking Brake and Actuation)
Parking Brake Cable Adjustment
- Vehicles With:
Rear Drum Brakes (General Procedures),
Parking Brake Cable Adjustment
- Vehicles With:
Rear Disc Brakes (General Procedures).
If the condition still exists. BLEED the brake
system. REFER to: (206-00 Brake System
-
General Information)
Brake System Bleeding (General Procedures),
Brake System Pressure Bleeding (General
Procedures). TEST the system for normal operation.
+ No
GO to D4.
Check for external brake and clutch system
leaks. REFER to the component tests.
Are any leaks found?
+ Yes
REPAIR as necessary. ADD fluid and BLEED
the brake system. REFER to: (206-00 Brake
System
- General Information)
Brake System Bleeding (General Procedures),
Brake System Pressure Bleeding (General
Procedures). TEST the system for normal operation.
+ No
GO to D5.
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